FA-66376 / Airline fare rule evaluation / Open access
Maximum stay months approximated as 30 days · case 01
A one-month maximum stay departing 1 January expires on 31 January instead of 1 February.
ROOT CAUSE
The maximum stay adds 30 days per month instead of advancing calendar months.
VERIFIED REPAIR
Advance calendar months with month-end and day clamping rules.
Unsuccessful approach: Thirty-one-day months over-extend validity in short months.
Case contract
Input {'depart','return' ISO dates,'rule':{'sat_night','min_days','max_months'}}. Saturday-night rule: return on or after the Sunday following the first Saturday on or after departure. Min stay: return - depart >= min_days. Max stay: return <= departure date plus max_months calendar months; a month-end departure maps to the target month end, otherwise day clamps to month length. Return failed rule names in order SAT, MIN, MAX.
Why this case matters
Stay restrictions mix weekday logic and calendar-month arithmetic with month-end and year-rollover rules.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
import calendar
N = 1
observations = []
def solve(x):
d = datetime.date.fromisoformat(x['depart'])
r = datetime.date.fromisoformat(x['return'])
rule = x['rule']
fails = []
if rule['sat_night']:
sun = d + datetime.timedelta(days=(5 - d.weekday()) % 7 + 1)
if r < sun: fails.append('SAT')
if (r - d).days < rule['min_days']: fails.append('MIN')
mo = d.month - 1 + rule['max_months']
y, mo = d.year + mo // 12, mo % 12 + 1
last = calendar.monthrange(y, mo)[1]
eom = d.day == calendar.monthrange(d.year, d.month)[1]
lim = d + datetime.timedelta(days=30 * rule['max_months'])
if r > lim: fails.append('MAX')
return fails
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-08', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-30', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-30', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-11', 'return': '2028-01-10', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, []], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-14', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, []], ['sampled case 1', {'depart': '2029-08-19', 'return': '2029-08-28', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 2}}, []], ['sampled case 2', {'depart': '2028-06-13', 'return': '2028-12-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 12}}, []], ['sampled case 3', {'depart': '2028-04-16', 'return': '2028-08-20', 'rule': {'sat_night': False, 'min_days': 1, 'max_months': 1}}, ['MAX']], ['regression: maximum stay month arithmetic', {'depart': '2029-11-16', 'return': '2030-10-20', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 11}}, ['MAX']]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-09', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-31', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-31', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-12', 'return': '2028-01-12', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, []], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-15', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, []], ['sampled case 1', {'depart': '2029-07-11', 'return': '2029-07-23', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 12}}, []], ['sampled case 2', {'depart': '2029-06-25', 'return': '2029-12-12', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 2}}, ['MAX']], ['sampled case 3', {'depart': '2029-02-02', 'return': '2030-02-22', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 6}}, ['MAX']], ['regression: maximum stay month arithmetic', {'depart': '2027-11-13', 'return': '2028-11-15', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 12}}, ['MAX']]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-10', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-29', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-29', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-13', 'return': '2028-01-14', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-16', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2027-10-05', 'return': '2027-10-14', 'rule': {'sat_night': True, 'min_days': 3, 'max_months': 6}}, []], ['sampled case 2', {'depart': '2028-04-06', 'return': '2028-10-12', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 11}}, []], ['sampled case 3', {'depart': '2027-11-12', 'return': '2027-11-21', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 2}}, []], ['regression: maximum stay month arithmetic', {'depart': '2027-08-11', 'return': '2028-07-11', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 11}}, []]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-11', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-30', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-30', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-14', 'return': '2028-01-16', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-17', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2027-06-01', 'return': '2027-06-09', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 1}}, []], ['sampled case 2', {'depart': '2028-03-04', 'return': '2028-06-07', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 6}}, []], ['sampled case 3', {'depart': '2029-03-17', 'return': '2029-03-25', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 12}}, []], ['regression: maximum stay month arithmetic', {'depart': '2027-04-05', 'return': '2028-03-01', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 11}}, []]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-12', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-31', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-31', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-15', 'return': '2028-01-18', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-18', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2029-08-05', 'return': '2030-07-02', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 11}}, []], ['sampled case 2', {'depart': '2028-05-10', 'return': '2028-05-12', 'rule': {'sat_night': False, 'min_days': 2, 'max_months': 11}}, []], ['sampled case 3', {'depart': '2027-09-03', 'return': '2027-09-03', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 6}}, ['SAT']]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| Sunday departure next-day return | ['SAT'] | ['SAT'] | Passed |
| Saturday departure Sunday return | [] | [] | Passed |
| Friday out Saturday back | ['SAT'] | ['SAT'] | Passed |
| month-end max stay | [] | [] | Passed |
| the 28th is not month end | ['MAX'] | ['MAX'] | Passed |
| Jan 31 plus one month | [] | [] | Passed |
| year rollover max stay | [] | [] | Passed |
| exact minimum stay | [] | [] | Passed |
| December twelve months | ['MAX'] | [] | Failed |
| sampled case 1 | [] | [] | Passed |
| sampled case 2 | [] | [] | Passed |
| sampled case 3 | ['MAX'] | ['MAX'] | Passed |
| regression: maximum stay month arithmetic | ['MAX'] | ['MAX'] | Passed |
SHA-256 / 02f7b69981c1cfc6df539058d36d810da6af42b2c409db6843adf350f518ff31
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
import calendar
N = 1
observations = []
def solve(x):
d = datetime.date.fromisoformat(x['depart'])
r = datetime.date.fromisoformat(x['return'])
rule = x['rule']
fails = []
if rule['sat_night']:
sun = d + datetime.timedelta(days=(5 - d.weekday()) % 7 + 1)
if r < sun: fails.append('SAT')
if (r - d).days < rule['min_days']: fails.append('MIN')
mo = d.month - 1 + rule['max_months']
y, mo = d.year + mo // 12, mo % 12 + 1
last = calendar.monthrange(y, mo)[1]
eom = d.day == calendar.monthrange(d.year, d.month)[1]
lim = d + datetime.timedelta(days=31 * rule['max_months'])
if r > lim: fails.append('MAX')
return fails
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-08', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-30', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-30', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-11', 'return': '2028-01-10', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, []], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-14', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, []], ['sampled case 1', {'depart': '2029-08-19', 'return': '2029-08-28', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 2}}, []], ['sampled case 2', {'depart': '2028-06-13', 'return': '2028-12-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 12}}, []], ['sampled case 3', {'depart': '2028-04-16', 'return': '2028-08-20', 'rule': {'sat_night': False, 'min_days': 1, 'max_months': 1}}, ['MAX']], ['regression: maximum stay month arithmetic', {'depart': '2029-11-16', 'return': '2030-10-20', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 11}}, ['MAX']]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-09', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-31', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-31', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-12', 'return': '2028-01-12', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, []], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-15', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, []], ['sampled case 1', {'depart': '2029-07-11', 'return': '2029-07-23', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 12}}, []], ['sampled case 2', {'depart': '2029-06-25', 'return': '2029-12-12', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 2}}, ['MAX']], ['sampled case 3', {'depart': '2029-02-02', 'return': '2030-02-22', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 6}}, ['MAX']], ['regression: maximum stay month arithmetic', {'depart': '2027-11-13', 'return': '2028-11-15', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 12}}, ['MAX']]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-10', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-29', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-29', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-13', 'return': '2028-01-14', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-16', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2027-10-05', 'return': '2027-10-14', 'rule': {'sat_night': True, 'min_days': 3, 'max_months': 6}}, []], ['sampled case 2', {'depart': '2028-04-06', 'return': '2028-10-12', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 11}}, []], ['sampled case 3', {'depart': '2027-11-12', 'return': '2027-11-21', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 2}}, []], ['regression: maximum stay month arithmetic', {'depart': '2027-08-11', 'return': '2028-07-11', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 11}}, []]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-11', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-30', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-30', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-14', 'return': '2028-01-16', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-17', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2027-06-01', 'return': '2027-06-09', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 1}}, []], ['sampled case 2', {'depart': '2028-03-04', 'return': '2028-06-07', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 6}}, []], ['sampled case 3', {'depart': '2029-03-17', 'return': '2029-03-25', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 12}}, []], ['regression: maximum stay month arithmetic', {'depart': '2027-04-05', 'return': '2028-03-01', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 11}}, []]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-12', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-31', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-31', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-15', 'return': '2028-01-18', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-18', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2029-08-05', 'return': '2030-07-02', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 11}}, []], ['sampled case 2', {'depart': '2028-05-10', 'return': '2028-05-12', 'rule': {'sat_night': False, 'min_days': 2, 'max_months': 11}}, []], ['sampled case 3', {'depart': '2027-09-03', 'return': '2027-09-03', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 6}}, ['SAT']]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| Sunday departure next-day return | ['SAT'] | ['SAT'] | Passed |
| Saturday departure Sunday return | [] | [] | Passed |
| Friday out Saturday back | ['SAT'] | ['SAT'] | Passed |
| month-end max stay | [] | [] | Passed |
| the 28th is not month end | ['MAX'] | ['MAX'] | Passed |
| Jan 31 plus one month | [] | [] | Passed |
| year rollover max stay | [] | [] | Passed |
| exact minimum stay | [] | [] | Passed |
| December twelve months | [] | [] | Passed |
| sampled case 1 | [] | [] | Passed |
| sampled case 2 | [] | [] | Passed |
| sampled case 3 | ['MAX'] | ['MAX'] | Passed |
| regression: maximum stay month arithmetic | [] | ['MAX'] | Failed |
SHA-256 / c65ccfc3dba65744ea3708f67c8bb0eaa93f59d235300a0aaf40d3747b1c5d7d
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import datetime
import calendar
N = 1
observations = []
def solve(x):
d = datetime.date.fromisoformat(x['depart'])
r = datetime.date.fromisoformat(x['return'])
rule = x['rule']
fails = []
if rule['sat_night']:
sun = d + datetime.timedelta(days=(5 - d.weekday()) % 7 + 1)
if r < sun: fails.append('SAT')
if (r - d).days < rule['min_days']: fails.append('MIN')
mo = d.month - 1 + rule['max_months']
y, mo = d.year + mo // 12, mo % 12 + 1
last = calendar.monthrange(y, mo)[1]
eom = d.day == calendar.monthrange(d.year, d.month)[1]
lim = datetime.date(y, mo, last if eom else min(d.day, last))
if r > lim: fails.append('MAX')
return fails
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-08', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-30', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-30', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-11', 'return': '2028-01-10', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, []], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-14', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, []], ['sampled case 1', {'depart': '2029-08-19', 'return': '2029-08-28', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 2}}, []], ['sampled case 2', {'depart': '2028-06-13', 'return': '2028-12-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 12}}, []], ['sampled case 3', {'depart': '2028-04-16', 'return': '2028-08-20', 'rule': {'sat_night': False, 'min_days': 1, 'max_months': 1}}, ['MAX']], ['regression: maximum stay month arithmetic', {'depart': '2029-11-16', 'return': '2030-10-20', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 11}}, ['MAX']]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-09', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-31', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-31', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-12', 'return': '2028-01-12', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, []], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-15', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, []], ['sampled case 1', {'depart': '2029-07-11', 'return': '2029-07-23', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 12}}, []], ['sampled case 2', {'depart': '2029-06-25', 'return': '2029-12-12', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 2}}, ['MAX']], ['sampled case 3', {'depart': '2029-02-02', 'return': '2030-02-22', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 6}}, ['MAX']], ['regression: maximum stay month arithmetic', {'depart': '2027-11-13', 'return': '2028-11-15', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 12}}, ['MAX']]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-10', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-29', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-29', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-13', 'return': '2028-01-14', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-16', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2027-10-05', 'return': '2027-10-14', 'rule': {'sat_night': True, 'min_days': 3, 'max_months': 6}}, []], ['sampled case 2', {'depart': '2028-04-06', 'return': '2028-10-12', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 11}}, []], ['sampled case 3', {'depart': '2027-11-12', 'return': '2027-11-21', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 2}}, []], ['regression: maximum stay month arithmetic', {'depart': '2027-08-11', 'return': '2028-07-11', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 11}}, []]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-11', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-30', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-30', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-14', 'return': '2028-01-16', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-17', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2027-06-01', 'return': '2027-06-09', 'rule': {'sat_night': True, 'min_days': 7, 'max_months': 1}}, []], ['sampled case 2', {'depart': '2028-03-04', 'return': '2028-06-07', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 6}}, []], ['sampled case 3', {'depart': '2029-03-17', 'return': '2029-03-25', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 12}}, []], ['regression: maximum stay month arithmetic', {'depart': '2027-04-05', 'return': '2028-03-01', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 11}}, []]], [['Sunday departure next-day return', {'depart': '2027-03-07', 'return': '2027-03-12', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 1}}, ['SAT']], ['Saturday departure Sunday return', {'depart': '2027-03-13', 'return': '2027-03-14', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 1}}, []], ['Friday out Saturday back', {'depart': '2027-03-12', 'return': '2027-03-13', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 3}}, ['SAT']], ['month-end max stay', {'depart': '2027-02-28', 'return': '2027-03-31', 'rule': {'sat_night': False, 'min_days': 3, 'max_months': 1}}, []], ['the 28th is not month end', {'depart': '2027-04-28', 'return': '2027-05-31', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, ['MAX']], ['Jan 31 plus one month', {'depart': '2027-01-31', 'return': '2027-02-28', 'rule': {'sat_night': False, 'min_days': 0, 'max_months': 1}}, []], ['year rollover max stay', {'depart': '2027-11-15', 'return': '2028-01-18', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 2}}, ['MAX']], ['exact minimum stay', {'depart': '2027-06-01', 'return': '2027-06-08', 'rule': {'sat_night': False, 'min_days': 7, 'max_months': 12}}, []], ['December twelve months', {'depart': '2027-12-15', 'return': '2028-12-18', 'rule': {'sat_night': True, 'min_days': 2, 'max_months': 12}}, ['MAX']], ['sampled case 1', {'depart': '2029-08-05', 'return': '2030-07-02', 'rule': {'sat_night': True, 'min_days': 1, 'max_months': 11}}, []], ['sampled case 2', {'depart': '2028-05-10', 'return': '2028-05-12', 'rule': {'sat_night': False, 'min_days': 2, 'max_months': 11}}, []], ['sampled case 3', {'depart': '2027-09-03', 'return': '2027-09-03', 'rule': {'sat_night': True, 'min_days': 0, 'max_months': 6}}, ['SAT']]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| Sunday departure next-day return | ['SAT'] | ['SAT'] | Passed |
| Saturday departure Sunday return | [] | [] | Passed |
| Friday out Saturday back | ['SAT'] | ['SAT'] | Passed |
| month-end max stay | [] | [] | Passed |
| the 28th is not month end | ['MAX'] | ['MAX'] | Passed |
| Jan 31 plus one month | [] | [] | Passed |
| year rollover max stay | [] | [] | Passed |
| exact minimum stay | [] | [] | Passed |
| December twelve months | [] | [] | Passed |
| sampled case 1 | [] | [] | Passed |
| sampled case 2 | [] | [] | Passed |
| sampled case 3 | ['MAX'] | ['MAX'] | Passed |
| regression: maximum stay month arithmetic | ['MAX'] | ['MAX'] | Passed |
SHA-256 / 6fe758b6f9fb07a8bc4b470cb789dc85bce0ad4b95a5c353999ad84b6c5da06d
Verification & scope
A stipulated toy fare-rule contract with invented constants; it is not an ATPCO or carrier tariff implementation and makes no claim of industry-standard conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:47:42.836619+00:00.
Case digest / f64902ec0c8bc6438c8b79449837b35fa9655ab2e4f318b0af8e204c79ca3c8a